Outlet box



Jne 19, 1945. M. B. AUTlN, JR l n ,2,378,529

` 4 OUTLET BOX Filedoct. 24, (1940 ATTRNEYs 1 y vAnother feature of the present invention Patented June 19, 1.945

UNITED STATE-S PATENT OFFICE n 2,373,529 ff i Y OUTLET 130x"Y I n MerrittA Austin, Jr., Winnetka, Ill. Application october 24, 1940, serial No. 362,515 s claims. o1.2s52 4. 5)

v'Ihis invention relates to outlet boxes for electricalpsystems, and is'concerned more particularly with means for facilitating the insertion of `,flexible insulated conductorsv including l. cables orconduits, with preventing injury to the conductors or their insulationyand yet providing forthe firmv and rigid securement of the con- .ductors to the outlet box. y -E Heretofore,in the interior of outlet boxes there- Yhas been provided aclamping member which is fdrawn ,toward the bottom of the box by Aa screw to engage and hold the ,conduit entering through a knockout or pry-out holein thebox. Generally,

.the clamping member, having only. a one-way connection to the clamping screw, lies ina position blocking 'the entrancey to the box provided for by the knockout hole, thus necessitating-the of theentrance opening usually had to be performed by` hand, in.` spi-te of the presencer of. a spring. Besides this, the spring added to the .cost

of the device.

.A feature of the. present invention is thearl rangement between the clamping screw and the clampingplate so that by merely backing off orlunscrewing the screw, the clamping plate.is raisedso that the clamping surfaces thereof are clear of the entrance holes... This is accomplished, in the form of the invention herein disclosed,y by

providing a, flange on the clamping screw which engages a slot on the clamping plate and makes '3a two-wayvfdriving connection between the clamp-- ing screw vand the clamping plate, and thus, when .the clamping screw is retracted, the clamping plate isretractedwith it.

1 .Another dii'culty with outlet boxesas.hereto fore manufactured results from the fact that the knockoutfholefwas so placed `as to leave a ledge between Vthe, bottom ofthe outlet box andthe bottom ofthe hole. lThis ledge facilitated clamp-l ingof the conduit to the outlet box, but it also,

especially whenused with nonmetallic armored cable, tended to out into the cable and destroy the insulation.4 v

istiie. provision of the knockout or pry-out holes in 55 such a way that the bottom oi the hole coincides with the bottom wall of the outlet box, and the knockout piece is substantially flat at the bottom so that the flat edge of the bottom of the-box is presentedy to thev cable or conduit which is inserted therein.

To give a gripping action between the bottom of thebox and the conduit or cable Vdirectly under the surface of the clamping member, the

boxis indented slightly to form anat V-shaped rib which will indent non-metallic armored cable to an extent suicient to grip it without, however, l

cutting into theinsulation.

The clamping` plate cooperating withv the lribbed bottom wall of theoutlet box has vdown- .i Wardlyextending ribs to bear on lthe upperpart ofthe lconductor so as to apply pressurey thereto,

lparticularly the nonmetallic armored conduit,

both in vfront of and in back of the rib` in the bottomof the outlet box.v l f lAnother feature ofv this invention is the provision of a plasterear which, by simply reversing its mounting onthe outlet-box, mayk accommo- `date conveniently not only ordinary plaster and plaster board, but such heavier non-plaster wall boards as are. now commonly used.

Other features and .advantages willhe'rein- --after appear.-

sov

Referring to i the .accompanying drawing:

AFigure l'is a side elevational view of an outlet box according to the present invention.

Fig. 2 is an end view of the outlet box zshown .inFig.,1. k

Fig.-3 is a planelevation of the outlet box of Fig.1.\

Fig. .4 is a cross-section substantially along the yline 44Min F1823. y

r Fig. 5.is a fragmentary detail in cross' secti0n y substantiallyalong the line 5 5 in Fig. 3, showing a knockout 'for forming an aperture to receive Q a cable and 'an indentation forming a ridge for ing means yof the present invention.v

Fig: 7 is a fragmentary end -view of the.l outlet `box as shown in'Fig. 2, showing a, variation of the method of Vsecuring the fastener or bracket to .said outlet box.l

Fig. 8, is Aa detail in cross-section along the line 8-8 in Fig. 4, showing a cable clamp and draft .meanstherefon Fig. 9 is a view snniiarto Fig. s showing non# aperture of the outlet box.

Referring to the drawing, the outletbox is constructed of sheet metal or some other suitable material, and comprises a bottom wall I0, end walls II, and side walls I2. The end walls II and bottom wall I are shown as integral, while the side walls I2 are removable to permit a plurality of boxes to be used side by side to form a gang box. At the upper edges yoi the said end walls II are formed. aatta-ching'earsaIS forfsecuring `aaa .cover Plate to the box. "Semipunched'rportions or knockouts I4 are provided in the side walls, said knockouts having slots I5 for theinsertion of a screw` driver or other suitable tool, whereby the .said

knockout may be pried outward and remov e'd"'to` form apertures in the said wallszzthrough which electrical conductors may be led into rthe box. A similar knockout I6 in the bottom wallllf'is provided which upon removal provides an aperture suitable for receiving Aelectrical connections or -s'tud'or other Xture'supporting means.

ilnea'ch of the endf walls'-' II,'.tl1`ere"is a 'pairfof inverted yknockouts I'T having 4slots "I 8` for rer-noving'them by meanso'f ascrew driver. i

According to the present invention,'*'the knock- Vouts "II are D-shape'd and are fso'locate'd las to `have the'straight-eiigeof the D= 'coincidingiwith "the line 'forming' the junction o'f' the bottom #and yend walls'of the'box as distinguishe'dffromfaperrturesy spacedfromthe' bo-ttomwall-o'f thev box,in

which case a 'ledge is leftbetween'themargin of theaperture and thefbottomfwall, asjforin- .slid into thev boxjwith'out intererencewith any apertures' resulting 'from the rlnio'ckou'tsfl 4 in Fig. if

,1. By virtue ofthe.extensi on `of'saidapertures"to the plane of the Abottoniwa'll'of Athe' 'box, sucljl'con-` ductorsmay be clamped against thebottomlwall IKO .without 'danger ofrdamaging the `irfrsulation of said conductors, sinceany 'sharp "corners against" which .such .conductors are,` clamped uarecelinii' nated.

.Eurthen according .to .the present invention,

means are provided upon the bottom walLIU for engaging theinsulationcn covering of conductors,

for instance, the armor of a cablelZD .oLFig ,or the .nonmetal` armored xcable ZGaAofFig. ;p'osi- .tioned in ztheaperture. .An .indentation L2| `.is

formed ,said bottom'wall adjacent .the -lower edge of the .aperture I 9 fwhich #Ecrins` af Vfshaped 1 .transverse 'fridge f22 on the. inner surface-.of said bottom wall as shown in Fig.y 5 for engaging .the

fconduit. l

".Clamping means v:for .securing-al conduit. inesaid.

aperture comprises i. an .l-.-shaped=:clampi ng member 23 having one iflange124. extendingmarallelrto `fthe T'bottom wall IlIl .'for engaging. saidlconductor,

is formed with two curved wings" 216 iforfadapting in thecable-.engaging surface off-"saidiiangexpro- 2,378,529 f f f metal` armored cable clamped in position in the vide secure engagement between said clamping means and the surface of the cable.

The flange 25 extending upward from the flange 24 is adapted to cover the aperture I9 above said cable.

The clamping member 23 is adjustably secured to the bottom wall I0 of the box by draft means comprising a bolt 28 extending through a central hole 29 in flange 24, and threaded into the bottom wall IIJ. The head of said bolt is enlarged by a eange =which=-extends intozfanf aperture or slot 133| ...in theflange 25 adjacent its junction with the flange 24.

In order to facilitate assembly of the bolt 28 with the member 23, the hole 29 is extended into r'slot 3I, as shown in Fig. 8, insertion or removal f.of.f.bolt'28irequiring merely the tilting of the latter with reference to the member 23 to permit the flange'illftorlear'lthe upper edge of slot 3|.

..Tlpon rotating vthe bolt 28 for loosening the clamping member 23, the latter rises upward with -thel*headfofasaidfbolt by virtue" o'f-fthe engagement off'sai'denla'rgement 30with said slot f3 I ,f andupon "tightening, 'the head of bolt- '2 8 engages 'the edges of theho1el29 inthe-m'ember Asvfaresult, when i-t is desired to' insert a-.cable' intof'the'ap'erture I9,` bolt 2'8'beingu'rithdrawn,l the clamping "member is heldfclea'r `of Asaid aperture fproviding maximum convenience 'for inserting .'said '-c-able.

YWhen *the 'bolt '28 'fis itightened after inserting the cable; the latter 'is' clampedbetween 'iflange 24 fan'dfthe:bottomwall Ii oi'the'box, ridge'i2'2 on the '-'latterandzrid'ges"ZI'on vthe said flange se- #curly gripping `the insulation fof the loable `as k'shown"in"l?ig. T9. '.Flange l25=covers the' upper portion of-A aperture `vI 9 'above said came, an'df engage- `ment tof said -"flange with the'end walls-*I laguides ftheclampingmember23 into thedesired clampin'gpos-t'ion, and 4prevents tilting 'o'i A'said "member whereby flange "3D 'couldbecom'e"disengaged fro'm'slotL 'The f-inventionfaiso `comprises 'novel adjustable means for securing the outletbox 'to' aportion fof alwall structure. The latter means 'comprises 'a'pa'ir of'fa'steners y32, ea'cnhaving a harige T33 *which 'extends outward atrigh't :angles f` from f'the end walls rI'I of the box VandA which is 'provided `with means such as y"holes 3'4"fo'r securing'them "to a par-tv of 'a Wall structure.h A` bifurcated plate, comprising two parallel tongues`i35forming 'ajpas- "sage`36,fis"bent at 'right angles to ange S3 and is secured to the surface ofthe end wall'II -of 'the"box`by"means of set screws 37, I'extending 'through the'passage 936 and engaging the 'tongues i 3 5'on 'either' sidek thereof. fPreferably,1.thesurface "ofthelen'd wall II is indented as indiciat'ed'at'iS 'to .provide means for guiding the "edges off I'the v'tongues 35 andfor retaining the'flange 33 parallelto'tlie upperedgeof'thebox.'r

'Adjacent :the junction `-o'f 'tlieflange 'and tonguesj35,'the lpassage 'Bti-is" widened su'fliciently "'to 'accommodate the width vci 'attaching ear I3 A'on `theuprJI-zr edge of vend wall I4 I and isexten'ded 'intoflangeB-as shown .fat 39 to' permit rthe said fastener to be slid .upwar'dunt'il.itisiiushwith the` `upper edges of said box, *the fear I'3"f fltti ng into "the extended v.and "widened 'portion' of the jpassageway in the flange 33.` The" opening 39 4`which "communicateswith thep'assage S'Bis *also wider than 'the 'headsgof'the screws'3`I" whereby cit is possible 4.fior removal toI slide the 'member-'132 downwardpastthe'sai'dset'screwsrnerelybylobsening' the latter but without the necessity-'onremoving them.

754 If desiredjthe positiomof 'nieniberasishown ythicknesses of wall covering, such as wallboard, plaster, lath,.metal lath, etc.

Variations and modifications `may be made within the scope of this invention `and portions of the improvements may be used Without others.

t 1. In an outlet box comprising two adjoining angularly disposed walls and having an aperture in one of said walls for yreceiving an electrical conduit, said aperture having a straight edge'coinciding with the juncture of the two walls,l means adjacent said aperture for clamping an electrical conduit extending through the aperture and into the box against withdrawal therefrom, said means comprising stationary means carried by the other wall for engaging one side of said conduit; a movable clamping member for engaging the other side of said conduit; draft means threaded into I y said stationary means; and interengaging means on said'draft means and vsaid movable clamping member for moving the latter alternately and positively toward and away from said stationary means in response to rotation of said draft means. n

, 2. In an outlet; box comprising two adjacent walls forming a right angle and an aperture in one of said walls for receiving an electrical conduit, said aperture extending to the edge ofthe other wall at the junction of the two walls; means adjacent said aperture comprising a clamping member for clamp-ing an electrical conduit extending through the aperture and intothe box against the nonapertured wall, said member having a flange for engaging ,one side of said conduit, and a ange parallel to and engaging the apertured wall, l and extending away from the other wall; draft means threaded into the latter wall for engaging the flange in contact with said conduit for moving the clamping member toward said wall; and means formed in the Wall-engaging flange, and engaging a portion of said draft means for moving said clamping member away from said wall.

3. In an outlet box comprising two adjacent walls forminga right angle and-an aperture in one of said walls for receiving an electrical conduit, said aperture extending to the edge of the other wall at the junction of the two walls; means adjacent said aperture comprising a clamping member for clamping an electrical conduit ex- Vtending through said aperture and into the box against the nonapertured wall, said member having a flange for engaging the side of said conduit opposite the latter wall, and a ange parallel to and engaging the apertured wall, and extending away from the other wall; a bolt extending through the flange in rcontact with said conduit, and threaded into the conduit-engaging wall for .moving said clamping member toward said wall;

and a flange o-n the head of said bolt engaging an aperture in the wall-engaging ange of said clamping member, for moving said clamping member away from the conduit-engaging wall.

4. In an outlet box comprising two adjoining angularly disposed walls and an aperture in' one of said walls for receiving an electrical conduit, means adjacent said aperture for clamping an electrical conduit extending through said aperture and into the box against Withdrawal therefrom, said means comprising stationary means for engaging one side of the conduit, amovable clamping member for engaging the other side of the conduit and clamping it against the stationary means, draft means threaded into the other of said walls of the box and engaging said movable member for positively moving it toward the latter wall; and means carried by said movable member and releasably engaged and interlocked with said draft meansfor positively moving said member away from said wall, a portion of said movable member engaging the apertured wallto retain the member against rotation relative thereto.

5. In an outlet box comprising two adjacent walls forming a right angle, an aperture in one of said walls for receiving an electrical conduit;

means adjacent said aperture comprising a clamping member for clamp-ing an electrical conduit extending through the aperture and into the box against withdrawal therefrom, said clamping member having a flange for engaging one side of said conduit, and a flange parallel to and engaging the apertured wall extending away from the other wall; draft means threaded into n the latterwall forengaging the conduit-,engaging flange and moving the clamping member toward said wall; and means formed in the wall-engaging ange engaging a portion of said draft means for moving said clamping member positively away from said wall, said wall-engaging flange being disengageable from said draft means whereby said clamping member may be removed from said box witlhout removing said draft means from said wa l.

6. In an outlet box comprising two adjoining angularly disposed walls having an aperture in one of said walls for receiving an electrical conduit, clamping means adjacent said aperture for clamping the electrical conduit extending through the aperture and into the box against withdrawal therefrom, said means including a clamping member slidable over the wall having the aperture and draft means threaded into the other wall and having a continuous flange releasably interlocked with the clamping member to positivelyv ing member by a tilting movement of the member with respect to the draft means.

MERRITT B. AUSTIN, JR. 

